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Switches / Hubs





A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

Hello Experts,

I have a project that involves cisco hardware selection and I would like to know the MSRP pricing for the cisco hardware.

Is there a pricing list from Cisco that I can use as a reference to come up for budgeting reason.

trying to reverse engineer the fcoe network of a company we purchased.   On the vethernet interfaces that the vfc interfaces are bound to, i see  'bind interface Ethernet1/2 channel 7' specifying the physical interfaces.   what does the command channel7 refer to?    it's not a port-channel as there is not port-channel 7.    

From googling is see - channel Specifies that the virtual Ethernet interface be bound to a specified
EtherChannel interface.    But i can't find any port-channels 7.
I am trying to understand how you connect Access Switches (L2) to Distribution Switches (L3) and create redundancy.
As shown in the screenshot below , each Access Switch has 2 Trunks , one Trunk  to a separate L3 Switch.
Well, if I am understanding, L2 will have VLANs configured and VLANs will be Trunked to L3 Switches.
The DIstribution(L3) Switches can be connected to each other with 2 Links(though on the picture it shows one link) and for the 2 Links I am not sure if they  can be configured as L2 or L3 Etherchannel bundel?  Also probably the L3 switches can be configured with HSRP  and one Virtual IP address.

Assuming my statement above is correct.

- how do you make all VLANs on L2 switches talk to each other ? are you going to configure SVIs on each L3 Switch ?  then on L2 you configure Default Gateway for each VLAN to be the SVI ip address created on L3 Switches.?

you will configure VLANs on L2 switches  to have as the default gateway the unique  HSRP Virtual IP. ?

- in this scenario , assuming L3 (Distribution switches) are connected to each other through L3 Etherchannel, will it be necessary to have  STP running on Access Switches /Distribution Switches?

Thank you
I am trying to understand  in which scenario Alternate/Backup Ports can be used.
on the above Link they give example of a HUB , but I do not think anyone uses a Hub nowadays. However what if instead of a HUB as shown on the Link, we put  SwitchX with 2 uplinks connected to SW2
SwitchX is connect to other Downstream LAN

When doing Network design by Block as follows:

Each Block has few Access Switches connected to higher end distributed switches
Each High end Distributed switches connected to the Core Switches

let's say we have 5 Blocks.

If I understand User PCs will connect to Access Switches
What about the Servers ? they can connect to Access Switches , but if I understand when clients send requests, the traffic will go through Access switches to Distribution Switches to the Core Switches to reach the Servers.
Now it sounds like VLANs where the Servers are Should not be reached directly by Clients through Access Switches , but through the Itinerary (Access Switches(where Clients are connected) to DIstribution Switches to Core Switches then Back to DIstribution Switches then to Access Switches where the Servers are connected)

Hope my question is Clear

Thank you
I have a small home network, a Windows server and a windows PC, connected by ethernet via a switch.

I also have a 3G/4G device which provides internet by wifi to my laptop, tablet and phone.

The computers on the home network don't have wifi so I tried to get them online by running a cable from the 3G/4G device to the switch.

However the computers on the home network are still not seeing the internet... how come?
Hello, we just migrated to distributed switches for our VMs on a VMware 6 U2 cluster. Following the upgrade, our VMs are having trouble talking to each other when they are on different hosts. They can ping each other by name, but things like Windows traffic won't go through. Move the VMs the same host and they can talk just fine.

We've been on the phone for hours with VMware support and getting nowhere. Its an odd problem as this was working before the switch migration. But now even when we move the VMs back to standard switches the problems continue.

I know that's all pretty vague, but if anyone has some insight, I'd appreciate it.
Hi All,

I'd like to know which storage network technology is better in terms of performance when combining 2x Ethernet Cat6 cable to the NAS from the ESXi server ?


What I mean combining is by configuring the NIC teaming like LACP or 802.3ad in my Physical Server which is able to combine 4x Cat6 cable into the Cisco Switch 3850 and then connected to another server with the same 4x Cat6 cables, Windows Network shows the NIC Team connection is 4 Gbps :-)

So which one is better to combine in VMware ?
Hi experts.

Trying to find out what could be the best solution for this setup.
SonicWall TZ300
D-Link DGS-1210-28P
Phone Polycom VVX300

We will be implementing VoIP in our offices. Actually, the ip phone has 2 ports: 1 goes to the switch, and the other goes to the PC.
The VoIP subnet will be in 192.168.x.x network, the data subnet will be 10.40.x.x

I need to have both subnets communicate with other offices (VPNs) and with the WAN.

Thanks for any advise you could provide

Is there a command to leverage information on what user accounts logged into Cisco switches via SSH which will also determine the date and time of the access.
I had Cisco tac help me create some policies for qos for our voice traffic on our nexus 9k at the datacenter.  I think i understand what he did but am still a little cloudy.  hoping someone can clear up.    

We have 2 policy-maps, one with type queuing and one type qos  to classify and put in the priority queue.   Both of these policy maps have the same name.  

policy-map type queuing voice
policy-map type qos voice

Are these the same policy-maps with different types or 2 totally separate policy-maps where i could have used different names?
So Im at my wits end here.. this san has two management interface.. both are configured to be on the same subnet.. actually 1 ip apart. and  I can ping .5, but not .4

The patch cables have been tested good, the config in MDSM shows good.. the switch ports config for both ports are identical.  I've tried pinging .4 from two other subnets including VLAN 1... no dice.  What could give here?
I'm having trouble accessing an additional vlan across these two switches from my new HP 2920s.
I can access the default vlan 1 fine, but devices connected to ports tagged as voice, are connecting to DHCP on the lan.

I have a few Adtran 1638P that are connected together as well as connected to my servers and phone systems.
My default (lan) network is 10.0.x.x, and my voice network is 192.168.168.x.
On my Adtran's  we have the default vlan 1 for the lan, and vlan 99 for the voice.
Adtran switches are trunked together, and I've made a trunk for the connection to our new HP 2920's.

On the HP 2920, I've created a trunk for the 2 ports connecting to the Adtran 1638P.
I've tagged this trunk, as well as the ports used for phones.
I've also Untagged the ports using the default vlan.

Below is a shorten version of each config.
My primary questions is why does a phone plugged into port 4/28 on the HP switch connect to DHCP on my lan, and not connect to DHCP from the voice network?

Thanks for any assistance.

Adtran 1638P Configuration
hostname "Karp-1638P-SW10"
clock timezone -5-Eastern-Time
ip subnet-zero
ip classless
ip default-gateway
ip routing
domain-name "karp.int"
ip route-cache express
no auto-config
vlan 1
  name "Default"
vlan 99
  name "OLDNET"
interface gigabit-switchport 0/46
  description Link to SonicWall
  spanning-tree edgeport
  no shutdown
I received an excel with list of VLANs that were matched with different subnets. For example,
vlan 10  -
vlan 11  -
vlan 12  -
vlan 13  -
But how can I verify if this information in Cisco switch? I tried different commands (show vlan, show interface trunk...etc.) but still could not find such info? could someone please help?
Dear Experts,

How I can download log file from Cisco switch ?

sh archive log conf all ( for catalyst switches)
show accounting log (for nexus switches)

If I understand VLANs are Layer 2 concept , and they are the Broadcast boundary, which means the Broadcast on one Vlan does not propagate to another VLAN. However I would like an Expert to clarify some dark areas about VLANs.

-- are VLANs the boundary of STP. I mean if there is a Switching Loop on one VLAN, the Loop will stay just on that VLAN and it does go to other VLANs ?

--If we have VLAN10 on a Switch in Building1 and 10 miles away in Building 2 we have another Switch that has VLAN10 and both VLANs are in the same VTP domain. is that considered Bad practice ?

--if we need to make Vlan2050 with 510 or 508 hosts  has subnets to and to , to make it one VLAN for all wireless Access Points.

in other words, is it possible to have one VLAN for 2 subnets ?

Thank you
can anyone recommend a color printer that has wifi and can hook up to my iphone?
can anyone recommend a good reliable powers USB hub?
One of the switches at a building I deal with is no longer communicating with SolarWInds, I compared it to configuration of another switch and see nothing different.

I  typed "show ip route" command and noticed the following, please see screenshot

Please see attached files: - Server which has Solarwinds Installed - Domain Controller - Domain Controller (MX64 Router - DG) (Cisco Router-For Voice/Corp Lan)

I can't figure out why the switch is referencing (Solarwinds Server) and no "seeing" the Default Gateway of

Any thoughts would be appreciated.
Refer to diagram.  Can you configure HSRP between service switch 1 and service switch 2 if they aren't connected..?  The connection from the service switch to cores are L3.  Service switch to DMZ are L2.  Service switch to WLC is L2 portchannel.  

On Fiber cable , even though the end of the cable is connected to one port on the switch (fiber cable port), but it Transmits and Receives Frames at the same time
On copper cable if I am not wrong there are about 5 or 6 wires , twisted in pairs . Which of them do Transmit and Receive Frames?
and if there are TX/RX capabilities on copper cable then do we need to configure UDLD/Loop Guard ?

Thank you
We recently began noticing issues with our ATS when we added a new url to web application.  I've searched everywhere for information on how to understand the ATS diags.log but I haven't found anything that will help me decode these errors.  Nothing on the Apache site was too clear.  Has anyone experienced issues with Slow Requests from ATS.  Also

[Aug 13 21:05:56.242] Server {0x2b41ad211700} ERROR: [1746026] Slow Request: client_ip: url: api.mapbox.com:443/ status: 200 unique id:  bytes: 24092 fd: 0 client state: 0 server state: 0 ua_begin: 0.000 ua_read_header_done: 0.000 cache_open_read_begin: -1.000 cache_open_read_end: -1.000 dns_lookup_begin: 0.000 dns_lookup_end: 0.000 server_connect: 0.000 server_first_read: -1.000 server_read_header_done: -1.000 server_close: -1.000 ua_close: 30.859 sm_finish: 30.859
Considering the impact that STP Loop can cause in the Network, I would like to know in real world whether there is granularity in configuration to fend off the loop or just set up VLANs normal way, use the VLAN Interfaces to communicate between VLANs and ignore the granular configuration.

What I mean by granular, to cite just few examples:
- Manually configure for each VLAN a specific Switch to be the Root for that VLAN
- Manually configure Access ports to be Portfast and at the same time configure the Ports with BPDUGUARD
- Manually configure on each VLAN each Blocked port with Loop Guard and UDLD
-Manually configure each VLAN with Root Guad,

if that's the case there should be a Config Template, that encompasses all those concerns.

Any clarifications on that ?

Thank you
Hello Experts,

Can someone please show me how to default the vtp settings? I would like to reset the VTP domain name and mode, see image to blank or nothing.

Hello Experts,

I use Cisco IOU provided by flyxy.cn at http://91sec.blogspot.co.uk/2014/03/my-cisco-iou-racks-from-flyxj-iouv3.html

The Cisco L2 IOU 12 causes a lot of CPU usage causes high CPU usage. The high CPU usage is System not Users: more debugging shows that L2 IOU causes a lot of loopback traffic. It was suggested to use the following commands:

class-map match-all ARP
  match protocol arp

policy-map ARP-limit
  class ARP
   police rate 2 pps burst 20 packets peak-rate 7 pps
     conform-action transmit
     exceed-action drop
     violate-action drop


However, I don't see where to apply to policy. Can someone shed some light



Switches / Hubs





A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

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Switches / Hubs